The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Cerebral aneurysms occur in approximately 2% of the population. Approximately 30,000 aneurysms are treated annually in the USA. Within this therapy group, 23,000 aneurysms are embolized with coils while 7,000 are repaired endoluminally with flow diverting devices. Aneurysms grow from a weakness in a blood vessel. About 80% of aneurysms are less than 8 mm with the remainder growing to as large as 40 mm. During stent-assisted coiling, a stent (Boston Scientific's Neuroform® brand of device or J&J Cordis Enterprise® brand of device) structure is placed within the artery of the vessel with the aneurysm in an attempt to reconstruct the vessel wall at the neck of the aneurysm. Patients are typically anti-coagulated and anti-aggregated with a combination of aspirin and Plavix to mitigate the thrombo-embolic effects of a foreign body response.
However, patients with sub-arachnoid hemorrhage (SAH) are typically not candidates for stents due the prophylactic drug regimen to mitigate the thrombo-embolic complications. A second approach is to perform balloon-remodeling. In this technique, a very soft, conformable balloon (for example, the eV3 Hyperform® brand of device) typically is used for balloon-test-occlusion being placed in the artery at the neck to reconstruct the neck at the aneurysm origin.
However, during this technique, flow arrest is performed while the balloon is inflated. There is a risk of initiating an ischemic event during balloon remodeling and/or a thrombo-embolic event during flow arrest. Once both these techniques are performed, coil embolization of the aneurysm can be performed. During the stenting procedure, the stent may be permanently implanted. During balloon remodeling, the balloon is removed once embolization is completed. Coils thus remain state-of-the-art treatment.
In addition, devices discussed so far, are typically visualized by markers at both the distal and proximal ends only. Although these markers verify the placement and/or deployment of the devices within the artery in relation to the abnormality to be repaired, verification of the complete opening or apposition to the artery wall or aneurysm neck cannot be verified unless a contract enhanced CT is performed. The ability to visualize these devices implanted in the artery offers procedural and clinical safety and benefit. The instant teachings address this need.
In most cases, complete embolization of the aneurysm with currently known devices will typically require at least several coils and devices, and/or are incomplete treatment of the aneurysm because the wall apposition and neck reconstruction of the aneurysm neck is insufficient and the coils previously placed have moved, or the visualization of the neck reconstruction was non-existent and the physician was unable to verify the proper placement of embolization devices at the aneurysm neck. The difficulties of stabilizing known devices within an aneurysm or vesicle are multiplied when aneurysm necks are wide, or the inflow zone of the aneurysm is in a high shear area (e.g., at a curve or bifurcation).
Further, it is not uncommon that sufficient amounts of devices cannot be placed into the aneurysm without losing microcatheter access due to aneurysm, aneurysm neck or vesicle morphology. Additionally, currently known devices can often not readily be stabilized within the aneurysm due to their visibility, softness and inertness. Finally, electrolytic detachment needs to be managed efficiently with proper timing for embolic coil delivery. Times ranging between 5 and 14 seconds of detachment time are optional for systems as discussed herein.
Thus, there is still a need for improved devices and methods of embolization devices, and especially neurovascular embolization devices for cerebral aneurysms, which are electrolytically detachable.